This invention relates generally to methods and apparatus for storing and then providing precisely measured amounts of granular material(s) preparatory to further processing of the granular material(s), particularly for providing precisely measured amounts of plastic resin material(s) to plastics manufacturing and processing equipment such as plastic injection molding, compression molding and extrusion equipment. Specifically, the invention relates to improvements in gravimetric weigh scale blender apparatus which facilitate cleanout of the hopper compartments both during operation and between batches.